1. Field of the Invention
This invention relates to a method of production of solder coated conductor wiring wherein the solder coated conductor wiring is provided on a ceramic substrate.
2. Description of the Prior Art
In one method known in the art of production of solder coated conductor wiring, an Ag-Pd paste is applied to a ceramic substrate and formed into Ag-Pd conductor wiring by printing, drying and firing, and then the substrate is immersed in a molten solder to produce the solder coated conductor wiring. In another method known in the art, a ceramic substrate is formed thereon with a metal layer by thin filming techniques, and the thin metal film is formed thereon with conductors as by plating before having a coat of solder applied by plating to the conductors to provide the solder coated conductor wiring.
Some disadvantages are associated with the aforesaid methods of production of solder coated conductor wiring of the prior art. For one thing, the use of a molten solder produces a coat of solder of about 20 .mu.m in thickness, and the trouble of short-circuiting of the conductors would occur in the case of miniature wiring when the conductors have a spacing interval of less than 20 .mu.m. For another, when plating is relied on for applying a solder, difficulties would be experienced in adjusting the composition of the solder, making it difficult to form a solder coat of high corrosion resistance. Also, when electric parts are soldered together, the connections formed would tend to be poor in reliability.